/*
 * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.datatorrent.lib.math;

import java.util.HashMap;
import java.util.Map;

import com.datatorrent.lib.util.BaseNumberKeyValueOperator;
import com.datatorrent.lib.util.HighLow;
import com.datatorrent.lib.util.KeyValPair;
import com.datatorrent.lib.util.UnifierKeyValRange;

import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;
import com.datatorrent.api.StreamCodec;

/**
 *  This operator emits the range for each key at the end of window.
 * <p>
 * <br>
 * <b>StateFull : Yes</b>, values are computed over application window. <br>
 * <b>Partitions : Yes, </b> high/low values are each key is unified at output port. <br>
 * <br>
 * <b>Ports</b>:<br>
 * <b>data</b>: expects KeyValPair&lt;K,V extends Number&gt;<br>
 * <b>range</b>: emits KeyValPair&lt;K,HighLow&lt;V&gt;&gt;<br>
 * <br>
 * <b>Properties</b>:<br>
 * <b>inverse</b>: if set to true the key in the filter will block tuple<br>
 * <b>filterBy</b>: List of keys to filter on<br>
 * <br>
 * @displayName Range Key Value
 * @category Math
 * @tags range, number, comparison, key value
 * @since 0.3.3
 */
public class RangeKeyVal<K, V extends Number> extends
		BaseNumberKeyValueOperator<K, V>
{

	/**
	 * key/high value map.
	 */
	protected HashMap<K, V> high = new HashMap<K, V>();

	/**
	 * key/low value map.
	 */
	protected HashMap<K, V> low = new HashMap<K, V>();

	/**
	 *  Input port that takes a key value pair.
	 */
	public final transient DefaultInputPort<KeyValPair<K, V>> data = new DefaultInputPort<KeyValPair<K, V>>()
	{
		/**
		 * Process each key and computes new high and low.
		 */
		@Override
		public void process(KeyValPair<K, V> tuple)
		{
			K key = tuple.getKey();
			if (!doprocessKey(key) || (tuple.getValue() == null)) {
				return;
			}
			V val = low.get(key);
			V eval = tuple.getValue();
			if ((val == null) || (val.doubleValue() > eval.doubleValue())) {
				low.put(cloneKey(key), eval);
			}

			val = high.get(key);
			if ((val == null) || (val.doubleValue() < eval.doubleValue())) {
				high.put(cloneKey(key), eval);
			}
		}

		@Override
		public StreamCodec<KeyValPair<K, V>> getStreamCodec()
		{
			return getKeyValPairStreamCodec();
		}
	};

	/**
	 * Range output port to send out the high low range.
	 */
	public final transient DefaultOutputPort<KeyValPair<K, HighLow<V>>> range = new DefaultOutputPort<KeyValPair<K, HighLow<V>>>()
	{
		@Override
		public Unifier<KeyValPair<K, HighLow<V>>> getUnifier()
		{
			return new UnifierKeyValRange<K,V>();
		}
	};

	/**
	 * Emits range for each key. If no data is received, no emit is done Clears
	 * the internal data before return
	 */
	@Override
	public void endWindow()
	{
		for (Map.Entry<K, V> e : high.entrySet()) {
			range.emit(new KeyValPair<K, HighLow<V>>(e.getKey(), new HighLow(e
					.getValue(), low.get(e.getKey()))));
		}
		clearCache();
	}

	public void clearCache()
	{
		high.clear();
		low.clear();
	}
}